Evaluation of Indonesian Natural Products Curcuma mangga Val. and Etlingera elatior: Antibacterial Activity, Synergism, and Gel Formulation

Abstract

Skin acts as a crucial first physical barrier, thus successful bacterial penetration could cause various infections. Indonesian medicinal plants, ethanolic extracts of Etlingera elatior and Curcuma mangga Val. had been previously reported to possess antimicrobial activity against various skin pathogens, yet no study has been reported regarding the possible synergistic activity of these plants. Topical gel formulation was chosen as a delivery vehicle. The study aimed to evaluate the antimicrobial effect of Curcuma mangga Val. and Etlingera elatior, its potency for synergistic activity, as well as formulate topical gel from the extract combination. To investigate this, extraction, qualitative phytochemical screening, microdilution assay, synergistic checkerboard assay, Kruskal-Wallis statistical analysis, gel formulation and characterization were conducted. Etlingera elatior and Curcuma mangga Val. displayed inhibition against Bacillus subtilis (MIC 0.5 mg/mL) and possible synergistic activity between the two medicinal plants (0.0625 mg/mL Etlingera elatior + 0.0625 mg/mL Curcuma mangga Val, FIC 0.5 = synergistic). The combination was able to be formulated into hydrogel and obtained acceptable physicochemical properties, although further adjustment to adjust the desired viscosity, and spreading capacity of the standard gel formulation might be carried out.